Apologies in advance for the thin details on this one.
I sell a Magento extension. With the latest release, I've started getting an odd bug report from a few users. Specifically, after installing the extension, they report being unable to login to the admin, with login requests being redirected back to the login page, and without any error message displaying.
So, this sounds like the classic "can't set a cookie/instantiate a session" problem. Where this gets weird is they are able to login after 3 - 12 hours (that's an estimate). In other word, they encounter the problem, contact me for support, I write back, they report the problem has vanished. I also assume clearing their cookies and establishing a new session id will fix the problem, and recommend the same to users encountering it.
Has anyone here run into something similar, or can think of a reason this happens? I can't recreate the problem locally, but I've gotten enough reports that I'm convinced it's a legit problem.